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1
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12 package com.versant.core.jdo.externalizer;
13
14 import com.versant.core.common.BindingSupportImpl;
15 import com.versant.core.common.Utils;
16
17 import javax.jdo.PersistenceManager;
18 import java.lang.reflect.Constructor  ;
19 import java.lang.reflect.Method ;
20 import java.io.Externalizable ;
21 import java.io.ObjectInput ;
22 import java.io.IOException ;
23 import java.io.ObjectOutput ;
24
25
34 public class TypeAsStringExternalizer
35 implements Externalizer, Externalizable {
36
37 public static final String SHORT_NAME = "STRING";
38
39 private Class type;
40 private transient Constructor constructor;
41 private transient Method toExternalString;
42
43 public TypeAsStringExternalizer(Class type) {
44 this.type = type;
45 init();
46 }
47
48 public TypeAsStringExternalizer() {
49 }
50
51 private void init() {
52 try {
53 constructor = type.getConstructor(new Class []{String .class});
54 } catch (NoSuchMethodException e) {
55 throw BindingSupportImpl.getInstance().runtime(type +
56 " does not have a " +
57 "constructor that accepts a String", e);
58 }
59 try {
60 toExternalString = type.getMethod("toExternalString", null);
61 if (toExternalString.getReturnType() != String .class) {
62 throw BindingSupportImpl.getInstance().runtime(type +
63 ".toExternalString() does not " +
64 "return String");
65 }
66 } catch (NoSuchMethodException e) {
67 }
69 }
70
71 public Object toExternalForm(PersistenceManager pm, Object o) {
72 if (o == null) return null;
73 try {
74 return toExternalString == null
75 ? o.toString()
76 : (String )toExternalString.invoke(o, null);
77 } catch (Throwable x) {
78 throw BindingSupportImpl.getInstance().runtime("Unable to convert instance of " +
79 type.getName() + " using " +
80 (toExternalString == null ? "toString()" : "toExternalString()") +
81 ": " + x, x);
82 }
83 }
84
85 public Object fromExternalForm(PersistenceManager pm, Object o) {
86 if (o == null) return null;
87 if (!(o instanceof String )) {
88 throw BindingSupportImpl.getInstance().runtime(
89 "Expected String to create instance of " +
90 type.getName() + ", got: " + Utils.toString(o));
91 }
92 try {
93 return constructor.newInstance(new Object []{o});
94 } catch (Throwable x) {
95 throw BindingSupportImpl.getInstance().fatalDatastore(
96 "Unable to create instance of " +
97 type.getName() + " from '" + Utils.toString(o) + "': " + x, x);
98 }
99 }
100
101 public Class getExternalType() {
102 return String .class;
103 }
104
105 public void writeExternal(ObjectOutput out) throws IOException {
106 out.writeObject(type);
107 }
108
109 public void readExternal(ObjectInput in) throws IOException ,
110 ClassNotFoundException {
111 type = (Class )in.readObject();
112 init();
113 }
114 }
115
116 |
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